Coarse woody debris of Fagus sylvatica produced a quantitative organic carbon imprint in an andic soil

Coarse woody debris (CWD) is involved in important forest ecosystem functions and processes, e.g., habitat provision, water retention, and organic matter decomposition. However, a quantitative, CWD-produced soil organic carbon (SOC) imprint has not yet been detected, possibly due to lack of free adsorption sites on soil minerals. To circumvent this potential constraint, we selected plots with and without CWD in a beech (Fagus sylvatica L.) primeval forest in the West Carpathian volcanic range (Slovakia). Local andic soil contains abundant allophane and amorphous Fe-compounds as important SOC binding agents. The C concentration in the fine earth of sampled soils was determined by the dry combustion method. We established that organic carbon concentration decreased with depth from 0.20 kg kg(-1) (0.0-0.3 m) to 0.11 kg kg(-1) (0.3-0.5 m) in soil with CWD and from 0.13 kg kg(-1) (0.0-0.3 m) to 0.07 kg kg(-1) (0.3-0.5 m) in soil without CWD. The respective average differences in soil organic carbon concentration (0.07 kg kg(-1)) and stock (15.84 kg m(-2)) between the two series of plots within the upper 0.3 m were significant according to the t test (P < 0.05 or P < 0.01, respectively). Also, corresponding differences within the 0.3-0.5 m layer (0.04 kg kg(-1) and 5.51 kg m(-2)) were significant (P < 0.05, P < 0.001). Our results represent the first indication that CWD-produced SOC imprint may reach deeper than just a few centimeters in soils featuring high adsorption capacity, such as Andosols.